This part is a bitch to find. I had the same results as you with the
exception of the following;
I never found anything more on it either...
Abstract: .. The M51996A is equivalent to the M51976 with externally
resettable OVP overvoltage protection circuit.
Equivalent does not, alas, mean the smae pinout (as I disconvered when
looking at some ancient dual tracking regulator ICs recently.
Not much help but it is a start.
Best regards, Steven
On 5/29/10, Tony Duell <ard at p850ug1.demon.co.uk> wrote:
> I am looking for a pinout or datasheet for a chip labelled M51976FP. It
> appears to be made by Mitsubishi, it's a SMPSU controller in a 20 pin
> SOIC package.
> I have the data on the M51977, which is similar (I think), but some pins
> are clearly different.
I think in the end I found that hte 51977 was a lot closer than I first
thought. I'd mis-traced a coupld of pins (using multimeter probles on
SOIC pacakges is not easy...)
I figured out enough to know that IC was not the problem anyhow...